The broad, long-term objectives of this proposal are to fully characterize the mechanisms of growth, ion transport, epithelial- mesenchymal interactions of epithelial cells derived from human autosomal dominant polycystic kidney disease (ADPKD) liver cysts. Immortalized (continuous) cell lines of cyst-derived and normal intrahepatic biliary epithelium will be produced, using retroviruses to transduce immortalizing genes. The resulting cell lines will be characterized to confirm that they are epithelial in origin. We will develop monoclonal antibodies to classify the regional origin of cell lines, characterize transepithelial ion transport and its regulation in detail, and determine the effect of female sex steroids on cell growth and ion transport. Our preliminary results demonstrate that cyst-derived cells survive surgical excision and overnight delivery, grow readily in culture, are capable of being immortalized, and express the biliary epithelial cell phenotype. The study of well characterized, continuous cell lines derived from liver cysts of ADPKD patients is likely to yield important information about the mechanisms of both liver and kidney cyst growth and enlargement in ADPKD. Liver and mechanisms. and are affected by the same molecular and biochemical mechanisms because they carry the same genetic defect. As is the case for the autosomal recessive genetic disorder cystic fibrosis, the detailed study of multiple organs expressing the same transport defect is likely to yield novel insights as it is highly likely that similar transport and growth defects are exhibited by ADPKD liver and kidney cyst epithelia. The present studies will provide, for the first time, continuous cell lines carrying the ADPKD genetic defect. In addition to facilitating study of the growth and ion transport disorder expressed by cyst cells, these cell lines will be essential for gene complementation studies, once the ADPKD genetic locus is defined.